Virus-like program that spreads automatically to other computers by sending itself out by email or by any other means. A program that propagates itself by attacking other machines and copying itself to the affected machine.
Worms have self-replicating code that travels from machine to machine by various means. A worms first objective is merely propagation. Worms can be destructive depending on what payload they have been given. Worms may replace files, but do not insert themselves into files.
This infection sends notes to Facebook friends of people with infected computers, with subjects like:
"You look just awesome in this new movie."
Users are directed to a website, where they are told to download what is claimed to be an update of the Adobe Flash player.